On my forehand I need help. I know how to set my feet up and I know how to make contat with the ball and follow-through, but I'm a bit unsure about the backswing. A lot of players like Serena, Dementieva, Sharapova, ect. have two backswings where they bring their racquet back and then kind of bring it back a second time for the second part. My question is, how exactly are you supposed to do the second part? I ask because it just doesn't feel comfortable when I just bring the racquet down but at the same time when I do two backswings it turns out sloppy and too big.

When you bring your racquet back and then begin your stroke, imagine the racquet going in a circle type of motion. Make sure when you are making contact with the ball that you are swinging the racquet from low to high as well as hitting through the ball. This video shows it well: http://youtube.com/watch?v=aLu3ZPo2iGo

Supergrunt, not sure I can help but I'll try. Think of the first part as just the change the grip part. It isn't really part of your backswing. The important thing is to not start and stop, but make one smooth motion. One smooth circle. The top part of the circle is just to get it back, then let it drop down (the middle part of the circle) so that you are going low to high.

Serena is doing that in the video. She does kind of stop, but she is changing her grip and starting her should rotation. Once she starts the backswing, it is all one fluid motion.

I think once you get that down, then you can adjust however you feel comfortable. But making it too complicated will tend to just cause hitches - and then things break down under stress or loss of time preparing for hard shots

Supergrunt, not sure I can help but I'll try. Think of the first part as just the change the grip part. It isn't really part of your backswing. The important thing is to not start and stop, but make one smooth motion. One smooth circle. The top part of the circle is just to get it back, then let it drop down (the middle part of the circle) so that you are going low to high.

Serena is doing that in the video. She does kind of stop, but she is changing her grip and starting her should rotation. Once she starts the backswing, it is all one fluid motion.

I think once you get that down, then you can adjust however you feel comfortable. But making it too complicated will tend to just cause hitches - and then things break down under stress or loss of time preparing for hard shots

Question: I actually use the same forehand motion, but my coach calls it a "wind up" and says he wants to see me go straight back and forward, not do the wind up. Why? I think it has to do with prep time.

Well the circular motion is more for getting topspin. Your back and forward motion might be for just hitting flat shots or when you are pushed for time. I dono

The 'C' backswing is not for topspin. You get topspin by swinging low to high, which can be achieved by any backswing so long as you drop the racquet head below the level of the ball before contact and swing up.

The common factors in these forehands (and all good forehands) are
1. The Unit turn.
Roddick and Federer have already completed it when their clips start, but you can see Novak performing it in his video (which is why I put it first).
After he split-steps, he uses his left hand to turn the racquet to the right grip while outstretching the left hand and turning his shoulders. His feet are also going to be set up here as well (whether open or neutral stance; the feet set is is VERY IMPORTANT).
Pics of complete unit turns:

THe unit turn is VERY important because it sets you up to begin the stroke. What you can't tell from the pics, is that their FEET ARE LOADED. What that means is your body weight is loaded/placed on your back foot (right foot for righties).
This is important for the kinetic chain in your SWING to occur properly because your stroke starts from your feet.

2. WEIGHT TRANSFER
After loading the back foot, you start your swing by moving your weight forward. You will end your stroke on your front foot (left foot for righties). THis is important as you don't want to have your weight falling back when you hit the ball. This opens the racquet face and your ball will fly.

3. FIRM WRIST AT CONTACT
Regardless of grip, you want to have a firm wrist atcontact. For different styles, you may be more wristy or less before and after contact, but at contact that wrist is laid back and FIRM. Moving it will lead to shanking.

That's pretty much it. Everything else is subjective. You can finish over your shoulder or by your waist, hit with more or less spin, more open stance or closed stance; FIND WHAT WORKS FOR YOU!
ALso hit through the ball. No premature pulling up.

But that's why I thought clay courter's had such trouble on grass. Because they used this type of swing to get topspin (as well as more western grips) when playing on clay. It takes heaps of time to complete this swing and since the ball bounces slow on clay it is usefull for them to develop topspin. But they would have less time to complete this swing on grass because the bounces so low and fast. So they have to alter their swing (and sometimes grip) all together to get a flatter shot and give themselves more time to prepare for the ball.

I usually tell myself that I cannot lose, and that I will eventually come out with the win. So even if I am down 5-0 I still believe I can win (which I have once ). I guess this way of thinking does disappoint you more when you don't come back from say a 2-4 deficit. But its better to stay positive and actually fight, than think "oh i'm going to lose" and don't fight at all.